Flat grinding possibilities?

[Titian]

Greetings followers of the Tormek, I am considering converting to your sharpening religion but have some concerns which I'd appreciate some guidance from the converted.

Things I like; quality, tolerances, cool, health, however my concern is over hollow grinding. I understand it has it's place but for myself is a no no. For carving chisels at shallow angle or hard steel, it is not good plus the bevel guides the chisel, so it is a compromise I am reluctant to make.

To get around this the common method on standard grinders is to present the chisel at right angles to the wheel. Another alternative is to use the side of the wheel.

My current system is flat grinder with 7inch waterstones which has it's benefits but is cheap and nasty plastic with bad tolerances. However with the flat of the stone facing up there is good flexibility over how the tool can be presented to the stone, which I enjoy especially as most of my grinding is done freehand.

Regarding to tormek if the tool is presented at right angles then this negates the use of all the jigs that are available. If the side of the wheel is utilised this looks awkward ergonomically. There is available the Jet Wetstone Side Wheel Grinding Jig, which is possibility but looks like it would be placed inconveniently for any real practical use.

My current system was around 100 pounds/euros/dollars so I dont mind messing around with it to get the best or of it. However when spending £500+ on a machine I am reluctant to have to start messing about with it to get the best out of it.

My hope is that the T-8 would come with a universal support system for using and truing the side of the wheel easily but until that happens I would be interested to hear the views and experiences of the tormek converts.

Thanks

[Herman Trivilino]

Without a way to true and flatten the side of the Tormek grindstone, or jigs to hold the chisels in place, I doubt it would give satisfactory results. It seems the slight hollow grind would be a better option.

You do realize that the "hollow grind" is nothing but a slight concavity across the surface of the chisel bevel. What are you doing with your chisels that makes this hollow grind unacceptable?

[Ken S]

Welcome to the forum, Titian.

You ask a good question. I think "hollow grinding" is an overused phrase used by writers who spend more time reading than sharpening.  Yes, the Tormek ten inch (250mm) grinding wheel is not flat, and will produce a hollow grind.  However, the hollow created by the Tormek wheel is considerably less than that created by the standard six inch dry grinder.

In some circles, a slight hollow grind is considered desirable, as the front and back surfaces provide an easy platform for honing.  With the Tormek, that's neither here nor there. I don't see where there is any appreciable difference in the "strength of the edge".

If the slight hollow bothers you, it is easily removed with a few strokes of  final sharpening with a flat stone.  The hard work will have already been done in removing nicks or establishing the bevel angle.

In my opinion, using the flat side of the Tormek wheel, or any standard grinding wheel, is not a primary function for the grinder.  Yes, we all do it.  The Tormek's two inch thick wheel certainly won't fall apart.  It's too thick and the speed is slow. There are more accurate ways when flatness is critical.  Flattening chisel backs is usually a one time occasion. i have used the side of the Tormek wheel to remove a belly from the back of a chisel.  For close work I would use abrasive paper on plate glass of a freshly dressed water stone.

You correctly note Tormek's "quality, tolerances, cool, health".  These are some of the Tormek's strengths.  I think the hollow grind "problem" with Tormek's large wheel is more of a theoretical problem than a real world concern.
 
Do keep posting.

Ken

[Rob]

Angels dancing on the head of a pin??  Is that the correct phraseology Ken :-)

[Ken S]

Strange, Rob.  That exact phrase was going through my mind when I wrote my last post.
Maybe we do have a common language after all........

Ken

[Tormek moderator]

It all depends quite a bit on the type of carving tool under discussion, and the type of work it is being used for. I found most carvers got very excited when I pointed out two things to them. If you take a mid to large size tool, and hold a straight edge from edge to heel of the bevel, the hollow is barely perceptible. Yet when you lay the tool on the work, you get a very positive feedback from the tool as to when you have both front and back of the bevel on the wood. It is actually easier to feel when your tool is on plane than a flat bevel is, and the hollow is so slight as to never weaken the edge.

For others, "riding the bevel" in carving means being able to stay on the bevel while introducing a smooth curve. For this type of work, the bevel actually needs to be slightly convex, rather than straight or concave. I've always achieved this on the Tormek by tweaking the Universal Support in a tiny bit after the bevel is established. Then grinding again, removing the heel of the bevel....sometimes even doing this heel removal twice. When you then take it to the leather strop, you'll polish out the hard lines and leave a flowing curve.

Good luck in your decision. Unfortunately, there's no perfect answer, but this one gives you a very versatile system that is very easy to work with.

[Ken S]

Titian,

You remind me of myself in my younger days.  Please forgive me if I sound paternalistic.  I remember desiring the highest precision in several areas of my life (namely photography, machinist tools and woodworking).  Whether it's deviations of ten thousandths of an inch in a square or straightedge; lines per millimeter resolution in a photographic lens; megapixels in a digital image; or nano whatever in the keenness of an edge;  those of us who really care want the best.

This is not a bad thing. It is part of how we grow.

I did not purchase a Tormek in order to achieve better edges.  Most of my sharpening is basic, mostly chisels, planes, and knives.  I have oilstones from both grandfathers which produce very adequate edges for most work.  They have served me well for many years, although obtaining a good edge required a good deal of work.

Around twenty years ago I added water stones, which cut faster. What eventually sold me with the Tormek was being able to obtain fine edges with considerably less pain in my hands and no worry about overheating the steel (as with my dry grinder).

I still have and use an assortment of oil and water stones, files, and diamond tools, as well as my dry grinder and a belt grinder.  I would not be without them, although, increasingly, I turn to my Tormek.

The Tormek is not the fastest machine. It is, in skilled hands, very versatile and capable of producing fine edges. Make no mistake, there is a learning curve.  This characteristic is shared by a Stradivarius violin.  A Strad has a very long learning curve.

Almost every function of a Tormek can be completed better with other machines. The plane and chisel edges produced with a Tormek are surpassed, at least in theory, by a very skilled sharpener with waterstones going up to 30,000 grit.  I have not doubt that industrial surface grinders produce superior flat edges and that top of the line industrial knife sharpeners surpass the Tormek.

The question becomes, how much capital does one plan to invest and shop space to dedicate to sharpen a chisel or knife? While the Tormek is not inexpensive, it is capable of performing many jobs well.

I used to live near a small company which manufactured high quality industrail drill bits.  I am quite sure they would not use a Tormek in their process.  However, in my home workshop, my Tormek with the DBS-22 drill bit sharpener can produce some amazing results, primarily limited by my lack of experience rather than the jig itself.

I can quickly duplicate edges with my Tormek which took considerable effort to produce with oil and arkansas stones.  This gets back to your reservations about hollow ground edges.

I suggest you purchase a duplicate of several of your most used tools.  Sharpen one with your preferred methods.  Sharpen the other with the Tormek, complete with its hollow grind.  Use both tools.  Your fingers will tell you a lot.  Listen to your fingers. You may prefer one method; you may prefer the other. You will know. 

Your quest for accuracy will lead you in your path of developing a sense of what is necessary and what is theoretical. Enjoy the process; it is part of your growth.

Do keep us posted,

Ken

[Titian]

Thanks for your considered words, Ken and Torm Mod, certainly giving my fingers something to think about.

Today after some grinding and sharpening I had a chance to compare two chisels which were exactly the same, one with a flat grind and one with a hollow grind. There is still more research for my fingers to do however there was huge difference in the feel of the carve between the chisels. On first impressions there are allot more angels on the flat grind, I found it a cleaner and more controllable cut. I wasn't expecting such a difference and it is a totally subjective personal experience. There are some other changes and experiments I wish to do but just to say thanks and these fingers are working on it and thanks for the guidance.

While doing my research I was also investigating how I would use a tormek machine to produce a flat grind and I believe is would be very suitable for that, especially as the wheel is upright I can look right down the eye on the needle as I call it and check the enlightenment of the grind. Yes I would try using it correctly as with the instructions in the manual but once I'd done that I'll probably throw them away and start doing it wrongly, to get the result's I'm after.

So all I need to do now is start saving up

There are some other aspects which I feel are worth discussing but I'll check the forums so see if there are any old angels hiding in there and might start another topic.

Thanks all

[Ken S]

Titian,
I applaud you for doing your own experiantial research. I am not arguing for either the flat or hollow ground orthodoxy.  With the hollow ground edge you tried, do you happen to know the diameter of the grinding wheel used?

Keep posting; your exploration is interesting.

Ken

[Herman Trivilino]

Today after some grinding and sharpening I had a chance to compare two chisels which were exactly the same, one with a flat grind and one with a hollow grind.

How hollow is the grind? With the 250 mm Tormek grindstone it's too small for me to see. If I lay it on a bench stone and take a few swipes I can see that the grinding starts near the edges, proving there's a hollow grind. But it's so slight that after a few more swipes it's gone.

I'm curious as to how you established that the chisels were other wise identical. Did you examine them with a magnifier or perform any kind of test to see if they had both been sharpened the same? Small differences in the quality of the sharpening will definitely be noticable in the way the chisels perform.

[Titian]

Thanks for everyone's informed questions. I'm just doing this for myself to establish if I can distinguish the difference between a hollow grind or flat before I invest in a better power sharpener. So the method used are purely personal and just for my own experience.

I've started with a 8inch equivalent hollow as that was simple for myself to achieve. I'm planing to produce a hollow equivalent to 10inch over the next week or so to see how that feels. Then flatten that and explore some different techniques around that.

The two chisels are the same type I've just ground one flat and one hollow, the cut angle is near enough the same when lined up against each other. I've not counted the scratches or anything like that, I've just used an equivalent technique on both, sorry it's not more scientific but it's as close as I can do without to much fuss.

I'm happy that it's easy enough to flatten a hollow grind if required so it's not so much of an issue now but until you try you don't know. However currently I still don't know if I will be able to determine between a 10inch hollow grind or a flat one but I'm interested to see if it is perceivable. Then also to explore any advantages or disadvantages it might bring.

Thanks again for every-ones tormek informed contributions.

[Rob]

I'll make one comment about honing hollow ground edges on an oil or water stone.  On another woodworking forum I frequent, debate rages constantly about which method is best. One thing pretty much all the protagonists agree on is that a hollow ground chisel or plane iron is easier to hone because of the two points of contact ie the heel and the toe.  Users generally report (as Ken did earlier in this thread) that they can feel the two points register on the stone and therefore feel confident in beginning the stroke of the hone.  With a perfectly flat bevel users generally report the "feel" of perfect bevel registration is less pronounced as there is one continuous surface rather than two.

I myself use bench tools straight off the machines and find that level of sharpness perfectly satisfactory so I cant comment personally. But then I only do the smallest amount of carving to add to turned pieces sometimes.

[Ken S]

My introduction to hollow grinding was from an old carpenter.  In 1972 I purchased several of his tools and his workbench.  At the time, he was eighty four and no longer using them.  He had a long a varied career as a carpenter, including working in Florida during "the boom" (1920s).  He told me he liked being able to touch up the hollow ground edges of his planes with a file.  I did not know enough at the time to inquire what coarseness of file he used.  Today we are generally limited to the ubitquous mill files in bastard coarseness (a perfectly respectable term denoting the most coarse grade generally available). Second cut and smooth files are available at more specialized industrial stores.  I suspect the old carpenter used one of these grades.

For anyone working in the field away from a grinder, doing touch up sharpening with files would be quick and avoid the mess of oilstones.  Doors were not prehung then.  He would have spent many hours fitting hinges and locks, as well as fitting the doors themselves.  He bemoaned yellow pine doors, which, being harder than regular pine, took a lot longer to fit.

I have three smaller tool chests this man built during World War II.  He was working for Goodyear Aerospace in Akron, Ohio and occasionally had to look busy during slow periods when an inspector might be present.  These chests are simply made with dado joints, not a dovetail, finger joint or mortise and tenon in the lot. However, in spite of their simplicity, the workmanship is neat and the chests are quite solid seventy years later.

My grandfather made chairs in his home workshop during the 1930s.  I have inherited many of his tools, including his sharpening equipment.  He used a very simple belt driven open grinder with a very primitive rest and the much criticized gray stones. He used a combination Norton India bench stone and a leather strop tacked to a piece of wood.  His level of craft was very fine, and his edges sharp and precise.

Today I have but a fraction of the skill these two men had developed.  What I do have is better sharpening equipment.  Even with my grandfather's old India stone, I can work more quickly with the advent of flat diamond dressing plates.  They not only keep the stone flat; they keep its cutting edge refreshed. However, the flattened and refreshed oilstone doesn't get much use now.  The Tormek allows me to do the same sharpening much more quickly with less effort and more precision.

Tormek has added the black and Japanese wheels to increase its range of cutting capability.  I believe at some future date we may see a diamond wheel for the Tormek. that would be superb (and probably priced that way).  To have the cool dust free cutting of the Tormek combined with the fast cutting of the diamond wheel with no need to re-true and refresh the stone would be a major advance.

If I just had a Tormek with a diamond wheel and the skill of my grandfather and the old carpenter............

Ken

ps I highly recommend having a set of bastard, second cut and smooth mill files with proper handles.  I have them is several sizes.  They see a lot of use, usually quick smoothing and fitting chores.

[Rob]

That's interesting Ken.  I inherited my Father's kit also (well split with my brother in fact) and he also sharpened with a 2 sided india/oil stone and had a piece of hide on wood for a strop and he also made very beautiful furniture.  Some large pieces as well as numerous smaller.  As he got into his 50's his skill really advanced and many a time I walked into the "garage" ie his workshop to be warmed by the combination smell of a paraffin heater and freshly planed pine.

To this day those are two of my favourite smells.  He also used fine files to tickle the sharpness back on just gone of tools rather than reboot the oil stones.  My equivalent for that has now become those inexpensive credit card sized fine diamond thingys. They're literally a credit card size, really thin with one side impregnated with diamonds and they work a treat on all manner of edges.  They're particularly useful to just bring back a skew that has gone off the boil.

That's become my go to file for odds and ends sharpening off the bigger tools.

[Titian]

My grandfather made violins I was told but alas I did not inherit any knowledge or tools.

The thought of grinding metal with diamond sends shivers down my back. I've tryed it on a set of cheap diamond plates and did not find it a pleasurable experience. It gave me the same sensation as those old Tom and Jerry cartoons when Tom would scratch his nails down the side of a ship but i was probably doing it wrong.